1. Field of the Invention
The present invention relates generally to the field of art which includes geometric instruments or similar devices having opposed contacts for ascertaining the measurement of an unknown distance. More particularly, the present invention relates to a measuring device in the form of a geometric instrument for ascertaining the diameter and depth location of a remote pipe or conduit that is not readily accessible for direct measurement.
2. Description of the Prior Art
The field of prior art relating to geometric instruments and similar measuring devices for ascertaining distances, diameters and other similar values is very old and replete with many different forms of such devices. One form of these devices includes two slidable members having a pair of opposed contact means secured to corresponding ends of the members. By extending and retracting one member with respect to the other, the contact means are caused to separate or close together until they come in contact with the article or extremities of the distance to be measured. The well known Vernier calipers manifest this basic type of structure. Generally speaking, devices of this nature are normally confined to relatively small, indoor applications and are basically manually held and operated tools. Their usefulness is generally limited to ascertaining the thicknesses and diameters of manufactured or fabricated parts and articles. To a limited extent, there have been prior attempts to adapt the basic opposed contact-type of geometric instrument to larger applications, such as the measurement of interior and external diameters of pipes and similar conduits.
However, in the surveying and engineering fields, there often exists the necessity for ascertaining the precise diameter and exact depth location of a pipe or conduit that is remotely located within an environment that is not readily accessible for direct measurement by means of known prior art measuring devices such as previously described. For example, a sewer or storm pipe may be buried many feet beneath the ground surface and communicate with a concrete casing that is accessible only through a sewer or manhole opening at ground level. In order to secure both the pipe diameter and depth location measurements, the surveyor or engineer must enter the sewer casing and obtain the measurements directly off of the pipe itself. This is obviously a time consuming process which is not without safety considerations for the individual working in such an environment.